Heretofore, barrier containment booms such as oil booms have been provided for containment of oil spills and other contaminating material on the surface of a body of water. Such booms have normally included a buoyant flotation member having a cover with a skirt extending downwardly from the cover and ballast for the skirt to maintain the position of the boom in a body of water. Flotation members may have incompressible flotation material. Alternatively, booms may be compressible in order that they may be stored in a smaller space than those with incompressible flotation material.
Inflatable booms exist in which a buoyancy chamber is provided for applying pressurized air. An air valve is closed when the chamber is pressurized. The air valve is opened to evacuate the chamber and to store the boom in a coil or on a reel.
Self inflating booms exist in several forms which do not require the application of pressurized air to the buoyancy chamber. One boom exists in which springs are provided to inflate the boom via the atmosphere after it has been stored in an uninflated condition. An air intake valve is opened for inflation with the springs causing the cavity to expand partially. Air rushes into the cavity causing it to fully expand and provide flotation. The air intake valve is then closed to prevent water from entering the buoyancy chamber while the boom is deployed. When the boom is stored, it is rolled up or wound on a reel causing the springs to be compressed while air is forced out of the opened air valve. Such a boom may be stored in an uninflated condition by rolling it on a reel and providing a restraining strap or the like to prevent the springs from opening the boom. While effective for providing a boom which may be stored in a smaller space than with a boom with incompressible flotation material, self inflating booms with spring mechanisms are expensive and sometimes unreliable due to their mechanisms on which they rely for self inflation. Furthermore, if the buoyancy chamber of such booms were to be punctured or rupture, water entering a section of the boom causes such section to sink. U.S. Pat. No. 4,244,819 illustrates a self inflatable boom which may be compressed for storage on a reel and self inflated when unreeled.
A common incompressible flotation material for prior art incompressible containment booms has been closed cell polyethylene material as shown in U.S. Pat. No. 4,188,155 dated Feb. 12, 1980, for example. Other, buoyant flotation members have included other closed cell materials, such as polyurethane, polyphinachloride, and polystyrene all of which are water impermeable. Such materials may be coated with a material to make the cellular material water impermeable such as illustrated in U.S. Pat. No. 4,244,819 dated Jan. 13, 1981. Booms which rely solely on incompressible materials for flotation, while inexpensive to manufacture and will not sink, are nevertheless expensive in terms of their cost of storage space. They require relatively large storage space on a ship, boat or dock awaiting their use in an emergency.
While many of the buoyant flotation members for incompressible containment booms have been of a closed cell foam material so that they are impervious to water, U.S. Pat. No. 3,708,982 dated Jan. 9, 1973 shows a compressible, self inflatable containment boom in which an open cell polyurethane foam material is utilized as a buoyant flotation member in an upper section. To maintain buoyancy of the foam material, the foam material is made water impervious by sealing the outer periphery of the foam material by application of a surface coating material, such as an elastomer. Such surface coating prevents oil and the like from reaching the permeable foam material. A lower water absorbent material is secured to the porous upper section by a conventional water repellent sealing adhesive to prevent any fluid seepage from the lower section, which is submerged in the water, to the upper section. The submerged lower section entraps water to provide necessary ballast for the upper section. A polyurethane foam material when used for both the upper and the lower sections of the '982 patent may be compressed about 25% of its original volume to permit ease of transportation and storage. An air valve is provided to permit upper section inflation during expansion and to permit compression of the upper section during exhausting of the air for storage of the boom. The '982 boom section is likely to sink if the surface coating material is ruptured or punctured, because water will enter the open cell foam of the upper section thereby causing it to sink.